Joblessness in Oregon slid below 8 percent this spring for the first time in more than four years, and the economy gained jobs for the eighth consecutive month.

Unemployment fell to 7.8 percent last month from an updated 7.9 percent in April, shows a new state report. It's the lowest rate since October 2008, the early months of the Great Recession. By May 2009, Oregon's jobless level ballooned to 11.6 percent. The four years since have been a long slog; unemployment falling about one point each year.

Oregon TODAY

7.8 percent unemployment

146,500unemployed workers

3,800jobs added in May

-May 2013,Oregon Employment Department

Last month, employers added an estimated 3,800 jobs, nearly half coming from the construction sector. The trade, transportation and utilities industry also added more jobs than expected, but hiring among manufacturers lagged.

The months-long hiring streak has helped pressure down unemployment. But fewer and fewer workers are in the labor market, partly behind the rate's decline.

In fact, Oregon's labor force participation is at a 40-year low: an average 63.2 percent in 2012. Economists expect it to keep falling, down 2 more points by 2020. The trend is occurring nationwide.

In a recent report, state economists say the aging workforce explains about half of the drop. And on the opposite end of the age spectrum, teens and 20-somethings waiting longer to enter the job market.

The recession has also played into the decline, the report says. But the number of discouraged workers in the state has fallen since 2010 -- an estimated 5,700 in 2012 -- making a relatively small impact on the overall labor force.

The percentage of adults in the labor force varies widely statewide, from 83.7 percent in Hood River County to 47.4 percent in
Curry County -- the only county where fewer than one in two adults either work or are looking for work.

The falling rate leaves fewer workers to support the population statewide, something that could weigh on Oregon's per capita personal income already lagging behind the nation.

Unemployment in Oregon is now just slightly higher than the U.S. average, 7.6 percent. The two-tenths of a percentage point difference is the smallest margin since May 2008.

A wider job market metric -- the U-6 rate -- counts
marginally attached workers and others working part time but would rather work full time. Oregon's U-6 rate was 17.2 percent, on average, last year, making it one of the highest rates in the U.S. It was 16.3 percent in April. The May rate was not yet available.

An estimated 146,400 were out of work last month, 18,800 fewer than the year before. Over that time frame, hourly wages ticked up just 13 cents, on average, from $22.11 to $22.24.